Adsorptive behavior of zeolitic imidazolate framework-8 towards anionic dye in aqueous media: Combined experimental and molecular docking study

Abstract

In the present work, zeolitic imidazole framework-8 (ZIF-8), a special class of metal organic framework (MOF) was prepared under a cleaner and greener synthesis route. ZIF-8 was characterized by using powder X-ray diffraction (PXRD), fourier transform infrared (FT-IR), scanning electron microscopy (SEM), transmission electron microscopy (TEM), thermo gravimetric analysis (TGA) and UV–Visible diffused reflectance spectroscopy (UV-DRS). The material was used to remove reactive blue-4 (RB4) from aqueous media via physical adsorption process. The adsorption kinetics, isotherms, effects of dose and ionic strengths were studied. The results of the above studies concluded that pseudo-second-order kinetics model and Freundlich isotherm fitted well with our experimental adsorption data. Thermodynamics parameters of adsorption like enthalpy, entropy and free energy were evaluated. The sorption process has taken place spontaneously and it was exothermic in nature. The adsorption of RB4 was discussed focusing on electrostatic attractions, pore-filling effects, π–π interactions and hydrogen bonding interactions. The results from this study indicated the ability of ZIF-8 to adsorb dye efficiently and its potential applications in wastewater treatment.